1. Field of the Invention
The present invention relates to a charging control device and an electricity storage system.
2. Description of Related Art
Alternating voltage supplied from a utility power source is converted into direct-current voltage by a charger, and a home-use battery is charged by controlling the charger. Electricity is stored in the battery in nighttime, and the stored electricity is used in daytime, because electricity cost is low in nighttime.
JP-B2-3827676 discloses an electricity storage system, and the system operates in a nighttime mode, a discharge mode, or a utility backup mode. In the nighttime mode, a battery of the system is charged by a utility power source, and nighttime rate is applied to the charging during nighttime. In the discharge mode, electricity is supplied to a load only from the battery in accordance with a consumption power of the load. In the utility backup mode, electricity is supplied to the load from the battery before the consumption power of the load becomes larger than a predetermined value. Further, electricity is supplied from the utility power source, after the consumption power of the load becomes larger than the predetermined value. Therefore, nighttime electricity can be effectively used, and use of daytime electricity can be reduced, when the load requires electricity beyond the predetermined value.
JP-A-2003-9418 discloses a method of charging and discharging a lead battery. A power conditioner having a two-way converter is arranged between a bus and the lead battery. A controller controls the battery to be charged at a level equal to or lower than 90% of its capacity in a usual time. Further, the controller controls the battery to have a full-charging at a predetermined timing. Thus, the battery can be restricted from having early deterioration. That is, cycle life of the battery can be made longer, and over discharge of the battery can be reduced.
However, JP-B2-3827676 or JP-A-2003-9418 fails to disclose a reducing of battery deterioration in nighttime. JP-A-2003-9418 discloses the reducing of the early battery deterioration, by reducing a frequency to perform the full-charging. However, JP-A-2003-9418 fails to disclose a method of constantly reducing deterioration.